The present invention relates generally to the field of biocompatible fluid delivery for ophthalmologic surgery, and more particularly relates to staining for enhanced performance in ophthalmological surgical procedures involving the removal of materials from the eye.
It is often desirable in the surgical field, and particularly in the field of microsurgery, such as ophthalmological surgery, to introduce stains, dyes or colorants (referred to collectively as xe2x80x9ccolorantxe2x80x9d) into a surgical site of a patient in order to enhance visual detail of the site. A suitable colorant must be biocompatible with the patient. For instance, it must be generally nontoxic and exhibit a pH compatible with the patient. Moreover, it must exhibit sufficient viscosity, surface and wetting characteristics so that it can be suitably directed to the region of interest, upon being administered to the patient.
A number of commercially available biocompatible colorants exist in the medical field, as the skilled artisan will appreciate. Without limitation, an example of one type of colorant that has attracted attention for certain applications is indocyanine green. That colorant has been used successfully in certain procedures, such as retinal angiograms, and other imaging studies of organs, owing largely to its ability to fluoresce, such as upon being suitably excited from an external energy source. U.S. Pat. No. 5,804,448 (Wang, et al); U.S. Pat. No. 5,576,013 (Williams, et al); U.S. Pat. No. 5,377,686 (O""Rourke et al); and U.S. Pat. No. 5,279,298 (Flower), all of which are expressly incorporated by reference herein.
Only recently has it been suggested that indocyanine green be used as an adjunct to cataract surgery to aid in visualizing the anterior capsule (the clear xe2x80x9cfrontxe2x80x9d membrane that encases the cloudy natural lens or xe2x80x9ccataractxe2x80x9d), in certain special cases where the anterior capsule is otherwise difficult to resolve optically. Though other colorants have been attempted for limited use in cataract surgery, the use of such colorants (for cataract surgery or other ophthalmological surgical procedures) still remains largely unexplored. Consequently, efficacy and other biocompatibility data is lacking or is dubious, i.e., is limited to highly specific conditions.
Moreover, it is believed that the use of a colorant such as indocyanine green has never been attempted for retinal surgery procedures. Recently, surgical removal or peeling of the internal-limiting membrane (xe2x80x9cILMxe2x80x9d) has been described as a potentially useful adjunct to vitreoretinal surgery, particularly in select macular hole cases, or other disorders characterized by an abnormal vitreoretinal interface. Typically, when the ILM is peeled, there are only subtle visible clues if any to determine the location of the border between unpeeled ILM and adjacent underlying retina or to define the best edge for continued peeling of the ILM. For example, where the ILM has been peeled, the underlying retina often acquires a rough or dull sheen, and there are often small intraretinal hemorrhages within the peeled area. However, it may be difficult to initiate the ILM peel and to visualize the border or edge of the membrane once ILM peeling has been started. It may also be difficult to continue an ILM peel if the edge is lost, or to determine the total extent of a peel (including from prior operations). Thus, difficult visualization of the ILM as well as firm attachment of the ILM to the underlying layers of the retina present potential technical challenges when trying to peel this membrane.
Ophthalmological surgery poses other unique constraints on the successful use of colorants to aid optical resolution. For example, the necessary tonicity of the colorant and any carrier that is used to deliver the colorant to the eye requires precise control over the composition and concentration of the colorant/carrier admixture. Some commercially available components for the admixture are provided as two-component systems (e.g., a granular precipitate and a solvent) that must be mixed in suitable proportions before administering to the patient. Moreover, the colorant systems typically have a relatively short shelf-life (e.g., commercially available indocyanine green commonly is marketed as having a fluorescence stability of only about 10 hours upon mixing).
References of potential interest to the present invention, all of which are expressly incorporated by reference, include:
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The present invention constitutes a substantial improvement in the surgical field, particularly in the ophthalmological surgical field. In accordance with the methods, devices, and systems of the present invention, there is provided an improved delivery vehicle for the administration of a biocompatible colorant into a surgical region of a patient. Generally, the methods of the present invention contemplate the steps of admixing at least two separate components to provide a colorant admixture for improving the optical resolution for a surgeon of a surgical region of a patient, and administering the admixture to the patient. In a particularly preferred embodiment, a cataract removal is performed on the patient followed by the implantation of an intraocular lens (IOL). In another particularly preferred embodiment, a thin layer the retina is removed.
The devices of the present invention generally include at least a first chamber for containing a first component of the colorant admixture and a second chamber for containing a second component of the colorant admixture. The first and second components are admixed in a third chamber (which may or may not include the first and second chambers). In one embodiment, the devices also are adapted to be in fluid communication with a suitable instrument for transferring the admixture from the device and into the surgical region.
In a particularly preferred embodiment, the colorant admixture includes indocyanine green in a sterile liquid solvent, and is provided in a container initially having two or more chambers. For instance, the solvent is provided in a first chamber, and the colorant is provided as a solid (e.g., freeze dried crystals) in a second chamber adjoining the first chamber and separated therefrom by a displaceable wall. Alternatively, the colorant is in liquid medium and may be provided in a single chamber container. The admixture is used for an ophthalmological surgical procedure, such as cataract or retinal surgery, where it provides a contrast medium (with or without fluorescence) for improving the optical resolution of the surgical region. During surgery, the wall is displaced and a third chamber effectively is created (which may include at least a portion of the first or second chambers), and the first and second components are admixed in the third chamber.
The present invention offers a number of significant advantages over the prior art. For example, without limitation, the present invention can be used in various surgical procedures heretofore not employed, such as cataract or retinal surgery, in order to improve the optical viewing characteristics and resolution of the surgical region. The present invention also permits for the administration of controlled doses of a colorant admixture, with insignificant waste of the admixture component (many of which typically are expensive and have relatively short shelf-lives), thereby reducing wasted colorant admixture and also allowing surgeons improved control over the concentration and dosage amounts of the admixture.